An experimental study of impulsively started turbulent axisymmetric jets
Department of Chemical Engineering, Indian Institute of Technology-Bombay, Mumbai, 400076, India
Corresponding author: a email@example.com
Published online: 20 February 2008
An impulsively started turbulent jet injected into quiescent surroundings with a constant inlet velocity has been studied experimentally. Results show that the jet length increases linearly with the square-root of time, over a wide range of Reynolds number calculated with respect to the jet diameter. The celerity factor, xf/t U, has been found to be nearly constant at 2.47 throughout with a 5% variance. Here, xf is the jet length, t is the time and U is the jet exit velocity. These results compare favourably with earlier results reported at lower Reynolds numbers. Finally, we present a simple model based on the integral energy balance of the turbulent boundary layer equation for an impulsively started turbulent axisymmetric jet. The model predicts a jet length that scales as, where d is the nozzle diameter and B(≈6.0) is the velocity-decay constant. This gives a celerity factor, in close agreement with the experiments.
PACS: 47.27.wg – Turbulent jets / 47.27.nb – Boundary layer turbulence
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008